> ## Documentation Index
> Fetch the complete documentation index at: https://docs.twine.se/llms.txt
> Use this file to discover all available pages before exploring further.

# System Integrations

> How Twine connects to and configures access to a single system

A **System Integration** is the configuration that defines how Twine connects to a single external system. Every system that Twine talks to - whether as a source, a destination, or both - is represented by a System Integration on the customer's organization.

## What a System Integration owns

A System Integration is responsible for everything that is specific to one system:

| Component              | Description                                                                                                                                                |
| ---------------------- | ---------------------------------------------------------------------------------------------------------------------------------------------------------- |
| **Connection details** | Credentials, endpoints, and any other configuration needed to authenticate and communicate with the system.                                                |
| **Property mappings**  | The translations between the system's data model and Twine's internal model. See [Property Mapping](/platform/property-mapping).                           |
| **Conditions**         | Integration-level filters that exclude entities from being processed by any domain mapping using this integration. See [Conditions](/platform/conditions). |

Property mappings and conditions live on the System Integration - not on the domain mapping - because they are properties of how Twine understands and handles data from that specific system, regardless of where the data is going next.

## Relationship to the Organization

A customer is represented in Twine by an **Organization**. An Organization can have any number of System Integrations - one for each system it wants Twine to connect to. Twine itself is also represented as a System Integration on every Organization, so that flows where Twine acts as the source or destination work the same way as flows between two external systems.

## Relationship to Domain Mappings

A [Domain Mapping](/platform/domain-mappings) connects exactly two System Integrations together for a given domain. The same System Integration can participate in multiple domain mappings, and it can act as the source in some and the target in others. Mixing source and target responsibilities for the same system is uncommon but supported.

In short:

* A **System Integration** defines how to access a single system, how to translate its data, and which entities to ignore.
* A **Domain Mapping** defines how to connect two System Integrations together for a specific kind of data.